Marijuana: Heavy Users Risk Changes to Brain

A new study finds that heavy marijuana use by adults could have long-term effects on the brain. What kinds of effects? WSJ's Jason Bellini has #TheShortAnswer.

This transcript has been automatically generated and may not be 100% accurate.

were talking about adults who use Merrill was ... and what impact the drug house on their mental health and intelligence ... experts been unable to make definitive statements ... of Tories can really say marijuana might do harmful things to the brain ... but that more research is needed ... you why Americans according to a recent poll ... ranked sugar and is more harmful than marijuana ... are they wrong ... maybe so but the report titled the long term effects of marijuana use on the brain ... is offering fresh evidence that a clinic user brain undergoes significant structural changes ... for those who use marijuana regularly over sixty years what kinds of changes using MRI scans researchers compared the brains of twenty ... three when marijuana users ... but on average eleven times per week ... to those of sixty two in on users the yellow area on this MRI scan shows the average amount that the gray matter density ... was diminished in the bilateral ... Orbital frontal ... or text of the marijuana users in ... the brain that's involved in decision making at the same time the MRI shows the marijuana users have ... greater activity than the control group ... in another section of the plan ... called the forceps mind or ... the white matter that connects the brain's frontal lobes the years according to researchers ... the pot smokers have more connections to facilitate communication between the ropes ... and ... the more efficient communication ... makes it more responsive to the environment why would marijuana users have higher connectivity ... and isn't that a good thing not necessarily report suggests this part of rain may be compensating fork gray matter losses however the study finds that over years of regular use ... the increase connections wither away ... I mean the train may be losing its ability to compensate for lost re matter ... then what happens ... the marijuana scientists not involved in this particular study says the longtime users ... could be at increased risk to be driven by a media rewards ... and not looking for more long term gratification ... may be more vulnerable to mood and anxiety problems the authors of the study admit they found no correlation between individuals IQ ... and reduced gray matter Google frontal cortex ... the weather heavy pot users have less grey matter to begin with making them more prone to using the drugs ... and if so whether marijuana made dough structural deficiencies works ... and the public is told ... more studies are needed so at this point set aside the emerging consensus among researchers that ... pot is harmful to the developing brains and adolescence ... in places where it's illegal ... to be the sciences think there should be a warning label on marijuana some who ... cares what Crystal was gone University of Wisconsin Milwaukee would have it said ... ITC marijuana can cause subtle cognitive deficits ... restructure abnormalities mood and sleep problems feel use is not recommended ... not recommended ... at least until the